System of communication



May 13, 1941. LA MAR E. HAYSLETT Erm. 2,241,663

SYSTEM oF COMMUNICATION Filed Sept. 3, 1940 3 Sheets-Sheet l May 13,1941. LA MAR E. HAYSLETT ET Al. 2,241,663

SYSTEM OF COMMUNI CAT ION 5 Sheets-Sheet 2 Filed Sept. 5, 1940 sneer srvan:

. HNHK E BY FAW/V05 /Z M May 13, 1941. LA MAR E. HAYSLETT E1- Al.2,241,663

SYSTEM OF COMMUNICATION Filed Sept. 5, 1940 3 Sheets-Sheet I5 sussckwsk/IOVI PI. a

Patented .May 13, 1941 SYSTEM F COMMUNICATION Ll Mal' E. Schmidt.

Hayllett, Kenmore, and Francis M. North Tonawanda., N.

Y., asslgnors to The Rudolph Wurlitzer Company, Cincinnati,

Ohio, a corporationy Applieeuen september s, 1940, seiei No. 355,140

(ci. ris-s) 7Clalms.

This invention relates to a system of communication particularly adaptedto the dispensing of music or other form of audible entertainment from acentral station to a plurality of subscribers stations.

One object of the invention is to increase the interest in entertainmentof this type in restaurants and other establishments where coin-operatedphonographs are generally installed.l This object is attained by theprovision of means by which a person desiring to hear a given selectionafter depositing a coin may make his selection orally by speakingdirectly to the phonograph in response to an inquiry from a centralstation operator transmitted through the speaker of the phonograph. Thisarrangement introduces a novel personal element in the operation ofmechanism of this kind which stimulates the interest of prospectivecustomers and increases the income from such apparatus.

Another object of the invention is to provide a central station systemfor dispensing entertainment which requires a minimum of Wiringconnection between the central station and subscribers stations. In thepreferred form of the apparatus described herein a single two-wiremetallic circuit is used between the central station and eachsubscribers station. Return talk and all necessary signals aretransmitted by a grounded simplex or half-phantom circuit connected tothe two-wire circuit without interfering in any way with thetransmission of programs and voice on the two-wire circuit.

Another object of the invention is to provide suitable apparatus bymeans of which ordinary mechanical selection of programs may beaccomplished during hours of slack business when it be lm mediatelynotified of the receipt of a coin whether or not all selections havebeen delivered for coins previously received.

In the preferred form ofthe invention described herein, there isprovided a central station having a plurality of phonograph mechanismseach provided with a pickup, turntable and associated operatingapparatus and each is not advantageous to have a central operator`normally connected through suitable amplifiers to a speaker at one of anumber of subscribers stations. The central station is also providedwith av coin registering device for each of the subscribers stations andsaid devices are normally connected to and operated by coin receivers atthe subscribers stations. The central station is also provided with atransmitter and receiver which may be any suitable type employed intelephone transmission or may be of the microphone and speaker type asdesired. Each subscribers station is provided with a transmitterpreferably of the microphone type and preferably installed in the samecabinet as the subscribers speaker. At the central station, keying meansare used for selectively connecting the central transmitter to thespeaker at any one of the subscribers stations and for connecting thecorresponding subscribers transmitter to the central station receiver.At each subscribers station there is provided in addition a local recordchanging phonograph mechanism equipped with the usual magazine switchand with a change-over switch adapted alternatively.

to connect the speaker and usual phono-amplifier to the local phonographmechanism or to the central station and to connect the coin receiver tothe magazine switch or tothe central station.`

Otherobjects and features of the invention will be understood from theaccompanying drawvings and the following description and claims:

Fig. 1 is a diagrammatic elevational view showing a preferredarrangement of the central station. Fig. 2 is aperspective view of thecentral station operators control board. Fig. 3 is a perspective view ofthe upper portion of a phonograph cabinet used at a subscribers station,with parts arranged for the ordinary mechanical oper. ation. Fig. 4 is asimilar view of the same cabinet with parts arranged for central stationoperation. Fig. 5 is a sectional view showing an arrangement of parts bywhich the mechanical selector keys of the cabinet shown in Figs. 3 and 4r are made inaccessible when central station operation is in use. Fig. 6is an elevational view partly in section showing a preferred form ofcoin register unit used with the central station control board of Fig.2. Fig. 7 is a diagram of electrical connections at the central station.Fig.`8 is a diagram of electrical connections at one of the subscribersstations.

Referring now particularly to Fig. 1, in which there is illustrated apreferred arrangement of the central station, there is provided a tableor Above the door 2I there is shelf I on which there is mounted acontrol board II shown in more detail in Fig. 2. On table I0 at eachside of the control board II and on shelves I2 there are provided aplurality of phonograph mechanisms I3 each equipped with a turntable I4,a pickup I5 and the necessary' mechanism, not shown, for rotating theturntable. The phonograph mechanisms I3, herein shown as ten in number,are conveniently placed to be operated by an operator seated before thecontrol board II. Each phonograph mechanism is provided with a checkoifswitch I6, the purpose of which will be described hereinafter. Atransmitter in the form of a microphone I1 is provided and may bemounted on a stand I8 placed connection with the electric circuits ofwhich they form a part.

Referring now to Fig. 3, showing a form of phonograph cabinet employedat the subscribers station, said cabinet is provided with the usualfront door 2I having a. glass window 22 therein through which a recordmagazine 23 and record changing mechanism of any well known form arevisible. Beneath the door 2I there is provided a plurality of selectorkeys 24 adapted to control the selection of records contained in themagazine 23 in accordance with similarly numbered program cards 25 whichare visible through the window 22. The cabinet also includes three coinreceivers 26 of any well known type adapted to receive coins ofdifferent denominations. provided a screen 21a behind which there ismounted a subscribers microphone 21. l

Referring now to Fig. 4, the same phonograph cabinet is shown arrangedfor central station operation. In

24 are covered by a panel 28 carrying the legend this arrangement theselector keys Select by Voice. Said panel is arranged as best shown inFig. 5 and is opening the door 2I, then closing and locking said door.At the same time, a selection list 29 printed on heavy cardboard orother suitable material and bearing the legend Select by Voice is placedin a suitable retainer behind the glass window 22. Said selection listeffectively hides the selection cards 25 and the mechanical recordchanging mechanism from the view of prospective customers. Theelectrical connections by which the changeover from mechanical tocentral station operation is performed are described hereinafter.

Central station electrical apparatus placed in position by firstinserting the panel and power for'. operating the central station isreceived from any suitable source on power mains 30 and preferably isthe volt alternating current. One of said power mains has connectedtherein a cutout switch 3I and the other carries the usual overload fuseprotection 32. A transformer 33 has its primary winding connected to themains 30 and is provided with a secondary winding 34 providingalternating current at a low voltage suitable for usual commercial 110heating the cathodes of the vacuum tubes used in the various amplifiersat the central station. The connection of the cathode heaters may beconventional and for that reason is not shown in the drawings. Directcurrent is supplied to a pair of distributory conductors 36a and 36hfrom a secondary winding 31 of transformer 33 con nected through aconventional rectifier unit 38. Said distributory conductors aregrounded through resistors 39 and 40 respectively. Resistor 39 isproportioned to maintain the conductor 36a at a suitable positivepotential to supply plate current for the several amplifier units and tooperate certain direct current relays. Resistor 40 is proportioned tomaintain conductor 36h at a negative potential of a few volts.

Other central station electrical apparatus .includes a phonographpreamplifier 4I associated with each of the phonograph pickups I5. Twoof said preampliers are shown in detail in Fig. 'I and the remainder maybe similar. A coin signal device 42 for each subscribers station is alsolocated at the central station and two of said devices are showndiagrammatically in Fig. 7. The central station transmitter I1 isequipped with a preamplifier 43 and the central station speaker I9 isequipped with an amplifier 44.

subscribers station electrical apparatus Referring now to Fig. 8, inwhich there is diagrammatically shown the electrical apparatus of onesubscribers station, power. for operating the station is supplied on apair of power mains 45 and 46 connected to any suitable source,preferably 110 volt alternating current. One of said power mains isprovided with a cutout switch 41 and the other carries a protecting fuse48. A changeover switch 49, herein shown as a twoposition multi-polarknife switch, is provided for the purpose of changeover from centralstation operation to local mechanical selection. When thrown to the leftin Fig. 8 for central station operation, said switch connects the powermains 45 and 46 to the primary winding of a transformer 50. Saidtransformer is equipped with a secondary winding 5I adapted to supplylow voltage alternating current for heating the cathodes of vacuum tubesused in the local microphone preamplifier 52 associated with the localmicrophone 21. Said microphone is preferably located behind the screen21a in the cabinet 20 as previously described. The transformer isprovided with a secondary winding 54 connected to a rectifier tube 55supplying direct current at a suitable potential above ground to aconductor 56.. Within the preamplifier 62 suitable plate voltages aresecured by conventional connections to the conductor 56.

Other apparatus at the subscribers station shownv diagrammatically inFig. 8 includes a phonograph mechanism indicated by name and providedwith a plckip 51, a speaker 58, an amplifler for said speaker indicatedPHONO AMP, a magazine switch indicated MS and a coin switch indicatedCOIN SW. All of said apparatus is preferably housed in the cabinet 20and may be of any construction suitable for coin Wiring and operationThe wiring connections shown in Figs. 7l and 8 may best be described inconnection with a description of the operation of the apparatus.

Operation-local mechanical selection Power for operating the phonographmechanism is supplied by direct connection to power main 5 and byconnection to power main 46 through conductor 59 and the magazine switchMS. When the changeover switch 49v is thrown to the right in Fig, 8, themagazine switch is connected to conductors 60 and 6| leading to the coinswitch and its operation is controlled by operation of the coin switch.At the same time, power for operating the phono-amplifier and speaker issupplied by direct connection to power main .45 and by connection topower main 46 through conductor 62, switch 49, conductor 63 and themagazine switch. The pickup 51 is connected to the phono-amplifierthrough switch 49 and conductor 64. These connections complete allcircuits necessary for local operation of the phonograph. When switch 49is thrown to ythe left, the pickup 51 is disconnected from the amplier,the coin switch is disconnected from the magazine switch and conductor62 is directly connected to power main 46 for operation of lthephono-amplifier and speaker 58 independently of Vthe magazine switch.

Phonograph transmission from central station 'Ihe output of each of thepickups I 5 at the central station is preamplied by its associatedamplifier 4| and is impressed on the primary winding of an output.transformer 69. The secondary winding 10 of said transformer has itsterminals connected to a pair of conductors 1| and 12 leading to thecorresponding subscribers station. The volume of the output impressed onthe conductors 1| and 12 is controlled by a variable resistor 13operated by control knob 13a on -the central station control board (Fig.2). At the subscribers station the conductors 1| and 12 are connected tothe terminals of the primary winding 14 of an input transformer 15. Thesecondary winding 16 of said transformer has one terminal grounded andthe other terminal connected through a series of resistance units 11,the changeover switch 49 and conductor 64 to the phono-amplifier andspeaker. The function of the resistance units 11 ls to modify the outputreceived from the transmission lines put transformer 1| and 12 to giveit substantially the same characteristics as the output of the pickup51.

By means of these connections, each of the phonograph units i3 at thecentral station is connected by a two-wire metallic circuit to thecorresponding subscribers station and each may be manually operated bythe central station operator to deliver a desired selection to thesubscribers speaker.

VfIVhe output `oir'the central station -transmitter |1 iswamplifeddbyitspreamplifier circuits 43 and 75 is impressed on the primary winding ofan out 80. The secondary winding 8i of said transformer has one terminalconnected through a switch operated by a key 82 to a bus line 84 and itsopposite terminal connected to a bus line 85, Said bus lines may beselectively connected to the conductors 1| and 12 of any givensubscribers station by operation of normally open switches controlled bypush buttons' 86, one of said push buttons -being provided for each ofthe subscribers stations. buttons 86 are mechanically interlocked in awell known manner so as to be mutually exclusive. That is, each pushbutton when pressed is latched in position to connect its associatedsubscribers station to the bus lines 84 and 85 andv automaticallyrelease Ito the normal position any of said push buttons which have beenpreviously pressed. A push button 81 is provided for manually releasingall of the buttons 8B when it is desired that none of the subscribersstations be connected to the bus lines. The volume of the output iscontrolled by a variable resistor 88 operated by a knob 88a on ythecontrol board (Fig 2). A meter 89 mounted on the control board isconnected across the bus lines 84 and to indicate the energy level of`the output to the subscribers station which may be connected to said buslines.

By means of the connections just described, the amplied output of thecentral station transmitter may be impressed on the two-wire metalliccircuit leading to any one of the subscribers stations by operation ofthe appropriate push button 86 and the talking key 82. Since thesecondaries of transformers 69 and 80 are in parallel connection, thevoice output may be superimposed on a musical program already inprogress of transmission. By manipulation of the volume controls 13 and88 the operator may adjust the combined output of the phonograph andvoice units to the proper level for transmission over commercialtelephone wires as indicated by the meter 89 and may reduce the volumeof the phonograph output to make the voice clearly audible, ifnecessary. The operator is aided in making the latter adjustment by thefact that the subscribers transmitter 21 is sufficiently close to thesubscribers speaker 58 so that the output of said speaker is fed back tothe central station receiver through the return talk circuits now to bedescribed.

Voice transmissiom-subscribers station to central station The output ofthe subscribers station transmitter 21 is amplified by its preamplifiercircuits 52 and is fed to the primary winding of an output transformer90, the secondary winding of which has one terminal connected to themidpoint of the Winding 14 of transformer 15 and the other terminalgrounded through a condenser 9| having proper capacity for freelytransmitting alternating currents of audible frequencies. At the centralstation the midpoint of winding 10 of each transformer 69 is connectedto one terminal of the primary windtransformer 93, the opposite terminalof which is grounded. The connections just described will be recognizedas a grounded simplex or half-phantom circuit in which alternatingcurrent energy induced in the secondary winding of transformer 90 istransmitted over conductors 1| and 12 in parallel, through windings 18and 92 to ground and returns-through The push ground and condenser Si totransformer 90. By proper balance of the windings 14 and 10 the currentnow in conductors 1| and 12 may be made equal.. the two currentcomponents have equal and opposite effects on the winding and so do notinterfere with transmission to the subscribers station.

@ne terminal oi the secondary winding of transformer @a is connectedthrough a condenser and a normally open switch controlled by push buttontt to a bus line 95 which is grounded through a resistor @d and apotentiometer 91. The opposite terminal is connected to ground throughdistributory conductor tito and resistance tu to complete a secondarycircuit. The potentiometer @i is operated by a knob 91a (Fig. 2) tovicy-passk a variable portion of the energy in the secondary circuit tothe amplier M for the central station transmitter I9. By thus varylngthe total resistance of the circuit the current iiow and voltage may becontrolled by the operator to keep the volumev level within the limitsrequired for transmission over commercial telephone lines. The level ofvolume is indicated by a meter 98 connected across the potentiometer 91.

A resistor 99 may be shunted across the potentiometer 91 by operation ofa normally open switch controlled by the talking key 82 and serves toreduce the output volume of speaker I9 when so connected. By this meansthe central station operator may have the beneiit of as large a volumefrom the speaker |9 as may be desired as long as the central stationtransmitter is not connected for transmission. When the later connectionis made, the volume level of the speaker |9 is automatically reduced toprevent the sound from feeding back into the transmitter l1 and causingan undesirable blare in the subscribers speaker.

Signal transmission When the changeover switch 49 at any subscribersstation is thrown to the left (Fig. 8), the conductors 60 and 6| leadingto the coin switch are disconnected from the magazine switch MS and areconnected respectively to the midpoint of transformer winding 14 throughthe secondary winding of transformer 90 and to one terminal of asecondary winding of transformer 50, the opposite terminal oiA which isgrounded. By this means the operation of the coin switch impresses onthe simplex transmission circuit to the central station a signal in theform of an alternating voltage having the frequency oi' the alternatingcurrent power supply. Said frequency is preferably 60 cycles per second.

At the central station the incoming low frequency coin signal istransmitted to the secondary circuit of transformer 93 in the samemanner as the incoming voice signals but the coin signal is preventedfrom reaching the amplier M by a reactance unit |0| and condenser |02connected in series across the input lines to said amplier and servingto lter out the lower fre-- quencies. A reactance |03 and condenser |04connected in series across the secondary terminals of transformer 93serve as a low pass lter to transmit the coin signal to a tube |05 havngsuitable electrodes and connections for rectification and' amplication.

The amplifier cathode |06 of said tube is grounded and the amplier anode|01 ls connected to an electromagnetic relay |08, the oping CurrentPOWQT mains .value the magnet posite terminal of which is connected tothe positive direct current distributory conductor 36a. The amplifiergrid |0557 is normally biased to cut ou by connection to conductor 36h.Each ltir-ne a coin signal fied current through cathode resistor |05Rincreases the grid potential to a point where sufficient current mayflow to operate relay |08. By means of these connections each momentaryclosure of the coin switch at one of the subscribers stationsmomentarily actuates the corresponding relay 508 at the central station.

Each momentary actuation of the electromagnet i0@ momentarily closes apair of normally open switches H2 and H3. The operation of switch i i2completes a circuit from the alternat- 30 for operation of anelectromagnetI ilfi. Said magnet forms part of a coin register deviceconsisting of a ratchet wheel i l5 normally urged in the clockwisedirection by a coil spring H6. Said ratchet Wheel is held in position byan escapement ||1 operated by an electromagnet ||8 and is moved againstthe action of spring IIB by means of a pawl ||9 operated by the magnetH4. The ratchet wheel ||5 carries a grounded contact member |20 adaptedto engage a contact segment |2|. In the normal idle position of theapparatus when no coin signals have been received from the subscribersstation, the contact member |20 is out of engagement with the contactsegment |2| as shown in Fig. 7. Upon receipt of a coin having unit ||4is momentarily actuated and operates the pawl ||9 to move the ratchetwheel ||5 to engage the contact members |20 and |2|. Successiveactuations of the magnet ||4 by receipt of additional coins or by coinsof more than unit value move the ratchet Wheelv I5 still farther in thecounter-clockwise direction. The contact segment |2| is madesuiiiciently long to maintain contact through any desired number of suchactuations. The checkoi magnet ||8 is operated by the push button switchI6 previously mentioned which completes a circuit for said magnet fromthe alternating current power mains 30. The magnet ||8 operates theescapement ||1 to permit the spring IIB to move the ratchet wheel I5 onestep in the clockwise direction. Obviously when the number of actuationsof magnet ||8 equals the number of coin values which have beenregistered by the magnet ||4, the contact member |20 has returned toinitial position and contact with the segment |2| is broken.

The engagement of contact members |20 .and |2| completes a. circuit fora pair of signal lamps |22 and |23, said circuit leading from asecondary Winding |24 of transformer 33, through a conductor |35 to saidlamps and thence through said contact members to ground and to agrounded terminal of winding |24. The lamp |22 is located on theoperators control board as shown in Fig. 2 and the lamp |23 ispositioned behind said board as best seen in Fig. 6. The control boardis provided with a. number of openings |34 behind each of which ispositioned the coin register unit stations. IIn Fig. 6 the ratchet wheel||5 of one of said units is indicated vand is mounted on an inclinedshaft |35 carrying a transparent frustoconical member |36. Said memberis positioned to be visible through the opening |34 and carries opaquefigures |31, one of which is visible through said openings at eachposition of the ratchet wheel H5. The lamp |23 positioned isreceived,the flow of rectiv 42 of one of the subscribers within thefrusto-conical member as shown in Fig. 6 increases the visibility of thenumbers |31.

By means of the construction just described, the signal lamps |22 and|23 are lighted for a given subscribers station when a coin has beendeposited at that station. Said lamps remain lighted until acorresponding number of selections have been checked oi by operation ofthe push buttons I6. The position of the ratchet wheel H and theindication of said position af- Iorded by the figures I3'I, visiblethroughthe opening |34, indicates to the central station operator howmany selections are still to be 'delivered to that subscribers station.

The operation of the switch II3 each time the electromagnet |08 isactuated completes a circuit from the positive direct current supplyline 36a through a resistor |38, an electromagnetic relay |39 and switch|03 -to ground. The relay |39 is of the type known as a stickrelay,-that is, it is provided with a holding circuit which is completedwhen the relay is actuated and holds the relay in energized conditioneven though the original actuating circuit is broken. The holdingcircuit leads from said relay, through a switch |40, a conductor I4I anda normally closed switch |42 to ground. The switch |42 is opened byactuation ofthe push button 80 at -the same time that the normally openswitches controlled by said push` button are closed. The switch |40 isclosed to complete the holding circuit by the actuation of the magnet|39 and retains the magnet in the actuated condition after switch I I3is opened until switch |42 has been opened.

The actuation of magnet |39 closes a switch |43 which completes acircuit from the alternating currentl supply line to a lamp I 44, theopposite terminal of which is grounded. Said lamp therefore is lightedas long as the relay |39 is energized. By means of this arrangement thelamp |44 is lighted when a coin has been deposited at the correspondingsubscribers station. When the operator presses the key 86 to connect thecentral station receiver I9 to the transmitter at the subscribersstation, the switch I 42 is opened, the relay |39 is deenergized andlamp |44 is extinguished. The lamp |44 thus performs a diiierentfunction than the lamps |22 and |23 since it indicates only that a coinhas been deposited but` that no connection has yet been made for returntalk from that particular subscribers station. If a number of coinvalues have been received at the subscribers station, the lamps |22 and|23 remain lighted until the corresponding number of selections havebeen delivered but the lamp |44 is extinguished as soon as the call fromthe subscribers station has been answered. If another coin is insertedbefore the lamps |22 and |23 are extinguished, the lamp |24 is againlighted to indicate the receipt of the additional coin and to notify theoperator that the subscribers station must again be connected for returntalk.

Rsum of operation station transmitter II to the subscribers speaker 58.The operator at the same time may operate the key 82 to complete thelast named connection and to reduce automatically 'the volume level ofthe central station speaker I9. The operator then requests the customerto name his choice of music and the customer answers by speakingdirectly to the phonograph cabinet. Itis also possible at this time thata pleasant-voiced central station operator may persuade the customer tomake an additional d eposit for more entertainment. When the customerhas named the selection or selections he desires, the operator manuallystarts the corresponding phonograph mechanism I3 and at the same timechecks orf one coin value by operating'the corresponding switch I6. Whenthere is no occasion for conversation over the line, the operator willordinarily release the key 82 to disconnect the central stationtransmitter I'I and will release all of the push buttons 86. However,the operator may at any time press one of the push buttons 86 and listenin on any of the subscribers'stations and may initiate conversationswith customers at said stations if desired.

The invention has been described in one of its preferred forms, thedetails of which may be varied between wide limits without departingfrom the scope of the invention as deiined in the appended claims.

The invention claimed is:

, 1. In a communication system having a central station and asubscribers station, a phonograph reproducer mechanism, a coin registerdevice, a telephone receiver, and a telephone transmitter located atsaid central station, a speaker, a transmitter and a coin receivingdevice at said subscribers station, a two-wire metallic electric circuitbetween said stations, said circuit connecting said reproducer mechanismand said speaker, keying means adapted to connect the central stationtransmitter in said circuit, electrical connections associated with saidtwo-wire circuit at each station and forming therewith a groundedhalf-phantom circuit between said sta. tions, said coin register deviceand said coin receiving device being connected in said half-phantomcircuit and said receiving device being adapted to actuate said registerdevice through' said circuit upon receipt of a coin, and keying meansadapted to connect the subscribers transmitter and the centralv stationreceiver through said half-phantom circuit.

2. The combination defined by claim 1 with the addition of a magazinephonograph mechanism at said subscribers station, a magazine switchconnected to control operation thereof, and a cutover switch andassociated wiring adapted to disconnect said speaker and coin receivingdevice from said two-wire circuit .and said half-phantom circuitrespectively and to connect the same to said magazine phonographmechanism and to said magazine switch respectively.

3. In a communication system having a cen- 'tral station and one or moresubscribers stations, a plurality of phonograph reproducer mechanisms, areceiver and a telephone transmitter located at said central station, aspeaker and a transmitter located at veach of said subscribers stations,electrical connections between said central station and each of saidsubscribers stations adapted to connect the speaker at each station to acorresponding reproducer mechanism, keying means associated with saidelectrical connections and adapted selectively to connect the centralstation receiver to any one of the subscrib Y ers transmitters,switching means adapted to connect the central station transmitter tothe speaker at the subscribers station whose transmitter is soconnected, an amplier operating the central station receiver, a volumecontrol unit associated therewith, and switching means automaticallyoperated with said iirst mentioned switching means and adapted tocontrol said volume control unit to reduce the volume level of thecentral station receiver when the central station transmitter is soconnected.

e. l'n a communication system having a central station and one or moresubscribers stations, a plurality of phonograph reproducer mechanisms, areceiver and a telephone transmitter located at said central station, aspeaker and a transmitter located at each of said subscribers stations,a two-wire metallic circuit connecting the speaker at each subscribersstation to a corresponding phonograph mechanism, electrical connectionsasociated with each of said two-wire circuits and forming therewith aplurality of corresponding grounded half-phantom circuits each connectedto the corresponding subscriberstransmitter, keying means adaptedselectively to connect the central station receiver to any one of saidhalf-phantom circuits and to condition a connection for the centralstation transmitter to the corresponding two-wire circuit, and switchingmeans adapted to complete said last mentioned connection.

5. In a communication system having a central station and one or moresubscribers stations, a plurality of phonograph reproducer mechanisms, areceiver and a telephone transmitter located at said central station, aspeaker and a transmitter located at each of said subscribers stations,a twor-wire metallic circuit connecting the speaker at each subscribersstation to a corresponding phonograph mechanism, electrical connectionsassociated with each of said two-wire circuits and forming therewith aplurality of corresponding grounded half-phantom circuits each connectedto the corresponding subscribers transmitter, keying means adaptedselectively to connect the central station receiver to any one of saidhalfphantom circuits and to condition a connection for the centralstation transmitter to the corresponding two-wire circuit, switchingmeans adapted to complete said last mentioned connection, an amplifieroperating the central station receiver, a volume control unit associatedtherewith, and switching means automatically operated with said rstmentioned switching means and adapted to control said volume controlunit to reduce the volume level of the central station receiver when thecentral station transmitter is so connected.

6. In a communication system having a central station and a subscribersstation, a phonograph reproducer mechanism, a coin register device, asignal relay, a signal lamp, a telephone receiver and a telephonetransmitter located at said central station, a speaker,'a transmitterand a coin receiving device at said subscribers station, electriccircuits between said stations adapted to connect the phonographreproducer and the central station transmitter to the speaker, toconnect the coin receiving switch to the coin register to actuate thelatter each time said switch is actuated and to connect the subscriberstransmitter to the central station receiver, a normally open switchconnected to make and break the last mentioned connection, an electriccircuit for said signal relay controlled by operation of said coinregister and actuating said relay, a hold-in circuit i'or said relayadapted to retain the same in actuated condition thereafter, a circuitfor said signal lamp controlled by said relay to actuate said lamp whensaid relay is actuated, and a normally closed switch in said hold-incircuit automatically operable with said normally open switch to releasesaid relay and extinguish said lamp when said normally open switch isclosed.

7. In a communication system having a phonograph mechanism at a. centralstation, and a speaker at a subscribers station electrically connectedto and operated by said phonograph mechanism, the combination of atransmitter at said subscribers station, a receiver at said centraistation, electric connections between said transmitter and' receiverincluding a normally open switch for making and breaking saidconnections, a coin operated switch at said subscrtbers station. asignal lamp at said central station, a normally closed switchautomatically operated with said normally open switch, and electricalmeans for actuating said lamp including a stick relay operated byactuation of said coin switch and released by opening of said normallyclosed switch.

LA MAR E. HAYSLE'IT. FRANCIS M. SCHMIDT.

